1. Field of the Invention
The present invention relates to a fundus camera which captures a fundus image of a subject's eye.
2. Description of the Related Art
As a method for capturing a fundus image, there is a fluorescent photographing method which inspects a running condition of a blood vessel of a subject's eye by using a fluorescent agent. In fluorescent photographing, a ruptured or difficult blood flowing portion of the vessel can be identified by checking a change of a blood flow on the fundus image of the subject's eye in real time. The change of the blood flow can be checked more minutely by stereoscopically capturing the fundus image. In typical stereoscopic capturing of the fundus image, a fundus camera body is slightly moved left and right, and two fundus images different from each other in parallax are captured. The two fundus images are arrayed left and right to be stereoscopically observed by naked eyes or polarized glasses.
However, the method based on stereoscopic observation by the naked eyes requires some skill, and hence the fundus images may not be satisfactorily observed in many cases. The method using the polarized glasses has a problem that a structure of an apparatus is complex.
In order to move the fundus camera body left and right to capture the two fundus images, the fundus images must be aligned to perform photographing twice. As compared with typical still image capturing of a posterior part of the fundus, the processing takes more time and labor
Japanese Patent Application Laid-Open No. 2003-024279 discusses a fundus camera which can stereoscopically observe fundus images by continuously displaying a plurality of images at predetermined time intervals, the fundus images having been captured by moving a camera body left and right.
Japanese Patent Application Laid-Open No. 2007-209433 discusses a fundus camera which can acquire two images having parallaxes without moving a fundus camera body by continuously performing a plurality of photographing operations by one shutter button operation and moving the position of a photographic diaphragm for each photographing operation.
However, in the case of the fundus camera discussed in Japanese Patent Application Laid-Open No. 2003-024279, the fundus camera body must be moved left and right to perform photographing, and the captured images must be stored first to be reproduced. Thus, real-time checking cannot be performed.
In the case of the fundus camera discussed in Japanese Patent Application Laid-Open No. 2007-209433, only a predetermined number of fundus images can be acquired within a predetermined period of time. Acquisition of fundus images and stereoscopic observation cannot be performed at any arbitrary timing.
In the above fundus camera, the fundus camera body or the photographic diaphragm is moved only left and right to capture images. Thus, no parallax information can be acquired nor any stereoscopic observation can be performed for horizontally-aligned vessels.